One example of oscillator circuits which use comparators is so-called relaxation oscillators. In relaxation oscillators of this type, a frequency of the oscillator circuit is typically determined by charging/discharging processes of a capacitor in an RC element. If, for example, a capacitor of this type is charged or discharged to a specific degree, an output terminal of a comparator, which compares a voltage present at the capacitor with a reference voltage, changes its output level, which in turn causes a change in a level of an output signal of the oscillator. Oscillators of this type can be used, for example, to generate oscillations in the range of up to more than 100 MHz, wherein oscillators of this type are used, in particular, below a few MHz, for example in the range of 32 kHz, since in this range they have a relatively low current consumption that decreases as the frequency decreases.
The frequency accuracy of oscillator circuits of this type is dependent, inter alia, on an accuracy of the comparator. In this case, comparators are supplied with a current, wherein the accuracy of the comparator is usually greater at a higher supply current than at a lower supply current. On the other hand, for many applications a lower current flow is desirable in order to save current and, consequently, for example in mobile applications, particularly if the oscillator circuit is required in a quiescent operating mode, to save energy in order to lengthen a rechargeable battery life.